The Mass is a participation in the one sacrifice of all time, Christ on the Cross. In that moment He merited for all mankind the possibility of salvation, should we choose to accept it. The Mass is a re-presentation of that same event in a different time and space.
The Church has always maintained that extra ecclesiam nulla salus “outside the Church, no salvation”. However, it is debatable to what “degree” that inclusion in the church is required. If there is no salvation outside the visible (i.e. Catholic) Church, then no Protestant would be saved. However, it is the current understanding among theologians that one can be inside the Church without formally being a member of the Catholic Church. Those who through invincible ignorance know nothing of the Church, yet strive to do what they know in their hearts is right may be saved. Those who recognize the Catholic Church for what she truly is and intend to be baptized, yet die before doing so may also be saved (“baptism of desire”). In addition, babies that have been baptised in Protestant churches yet whom have not reached the age of reason are also saved, as they would not be guilty of personal sin. For the rest of the Protestants, the debate rages on, as many may be in that state of “invincible ignorance”, taught from childhood to stay away from learning about the True Faith.
As for those who believe the Church to be true, yet refuse to join it, well…may God have mercy on their souls.
